Optimize includes across code base

src/updatecheck/UpdateChecker.cpp

@@ -25,6 +25,7 @@
 #include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
+#include <QNetworkReply>
 #include <QRegularExpression>
 
 const QString UpdateChecker::ErrorVersion("error");

src/updatecheck/UpdateChecker.h

@@ -18,7 +18,6 @@
 #ifndef KEEPASSXC_UPDATECHECK_H
 #define KEEPASSXC_UPDATECHECK_H
 #include <QObject>
-#include <QString>
 
 class QNetworkReply;